Design and control of vast DOF wet SMA array actuators

A new concept for an actuator array is presented where a vast number of actuators are contained within a small volume and are controlled in a scalable sense. This vast degree-of-freedom system utilizes an array of shape memory alloy wires embedded within a network of fluidic vessels. A matrix manifold and valve (MMV) system routes fluid from hot and cold reservoirs in order to control an array of N² SMA actuators using only 2N valves. A prototype MMV system containing a 4 by 4 array of wet SMA actuators is designed and implemented. Control strategies suitable for controlling MMV system that uses 2N valves to control N² actuators are presented. Two different protocols are presented and evaluated. The system error increases without bound under certain input conditions, since all the actuators cannot be activated at the same time. Simulations show that system error starts to go out of bound when the individual actuator is activated 25% of the time for the 4 by 4 arrays of the actuators.